Efficient preamble design and modulation schemes for wake-up packets in wlan with wake-up radio receivers

ABSTRACT

Systems and methods of transmitting and receiving a Wake-Up Radio (WUR) packet by using a simplified preamble structure that contains no training field. The preamble carries a signature sequence selected from a set of predefined sequences, each corresponding to a different data transmission rate. The preamble and the control information of the WUR packet are transmitted in the same rate as indicated by the selected sequence. Hence, a receiving WUR can determine the data transmission rate and locate the associated control information directly if a sequence that matches a predefined signature sequence is detected. The same sequence or in combination with an additional sequence in the preamble may also be used to indicate automatic gain control synchronization, packet type and other related information.

CROSSREFERENCE TO RELATED APPLICATION

This patent application claims priority and benefit of the U.S.Provisional Patent Application No. 62/483,969, entitled “EFFICIENTPREAMBLE DESIGN AND MODULATION SCHEMES FOR WAKE-UP PACKETS IN WLAN WITHWAKE-UP RADIO RECEIVERS,” filed on Apr. 11, 2017, the entire content ofwhich is herein incorporated by reference for all purposes.

TECHNICAL FIELD

Embodiments of the present disclosure relate generally to the field ofnetwork communication, and more specifically, to the field ofcommunication protocols used in wireless communication.

BACKGROUND OF THE INVENTION

Wireless local area networks (WLANs) and mobile communication deviceshave become increasingly ubiquitous, such as smart phones, wearabledevices, various sensors, Internet-of-Things (IoTs), etc. With theiroverall size constrained by portability requirements, such communicationdevices typically are powered by a built-in battery of limited chargingcapacity. Most workloads performed by a communication device can becommunication-driven and therefore the internal wireless radio is amajor power consumption source as it needs to remain operational toensure prompt responses to data communication requests.

To reduce power consumption by the wireless radios, some communicationdevices include a low-power wake-up radio (WUR) in addition to a mainradio that is used for data transmission and reception. When it is notinvolved in data communication tasks, the main radio can be placed intoa power conservation state, e.g., a sleeping mode or even turned off. Onthe other hand, the low-power WUR remains active and operates toactivate the main radio whenever the WUR receives a data communicationrequest that is directed to the main radio, e.g., in a form of a wake-upsignal transmitted from a WI-FI access point (AP).

Compared with a main radio with high rate data communicationcapabilities and complex processing functions, it is important that theWUR be a low-cost and low power consumption radio and yet is able toreceive and process a wake-up signal and accordingly activate the mainradio. For example, the nominal power consumption of a WUR can be 0.5˜1mW or even less.

In existent wireless communication protocols, the preamble of a packetusually has a complex structure with multiple training fields forcarrying training symbols. A receiving device needs to decode thesetraining symbols to determine the data transmission rate of thefollowing payload and accordingly resolve and payload. To reduce errorsin receiving and interpreting the training symbols, the symbols aretransmitted at a low fixed rate regardless of the data rate used fortransmitting the payload. However, this undesirably lowers channel usageefficiency and overall transmission efficiency.

SUMMARY OF THE INVENTION

Accordingly, systems and methods disclosed herein provide effectivewake-up signal communication protocols by enclosing adequate preambleinformation in a simplified mechanism in Wake-Up Radio (WUR) packets,and this mechanism enables a receiving device to detect and resolve thewake-up signals in a power-efficient and time-efficient manner as wellas with enhanced reliability.

Embodiments of the present disclosure use one or more particularsequences in the WUR packet preamble to indicate information which canbe used for a number of operations including packet detection, datatransmission rate detection, payload detection, automatic gain control(AGC) and/or frequency/timing synchronization. More specifically, thepreamble of a WUR packet has a sequence field, the value of which is asignature sequence selected from a set of predefined sequences. Eachpredefined sequence corresponds to a different data transmission rateused for transmitting both the preamble and the payload (or “controlinformation” herein) of a WUR packet. A WUR is capable of detecting anyof the predefined sequences in its corresponding data transmission rate,for example by using a set of parallel correlators. In some embodiments,the plurality of predefined sequences include a pair of complementarysequences which can be detected using a single correlator. The preambleand the control information may be modulated in accordance with On/OffKey modulation.

Thus, at a receiving device, responsive to detection of a signaturesequence from a received signal, the WUR on the device can treat thesignal as a WUR packet and resolves the ensuing control information in atransmission rate corresponding to the detected sequence. As a result,the WUR can generate a wake-up indication to activate the main radio. Insome embodiments, the preamble of a WUR packet is composed of one ormore sequence fields and has no other fields. The boundary between thepreamble and the following control information can be simply located bydetecting the end of the sequence. Each of the signature sequence mayadditionally indicate a WUR packet type. Also, there may be a sequencefield defined for containing a predefined sequence for indicatingautomatic gain control and synchronization settings.

According to embodiments of the present disclosure, the preamble in aWUR packet uses a predefined sequence to indicate a data transmissionrate, instead of using training symbols as in the conventional approach.The preamble and the control information are transmitted in the samedata transmission rate corresponding to the sequence. Thisadvantageously eliminates the need for transmitting training symbols ina lower data rate than the payload, and eliminates the need for decodingthe training symbols at a WUR. As a result, the WUR packet transmissionefficiency and WUR power efficiency can be significantly improved. Therelated circuitry design of a transmitter and the WUR can beadvantageously simplified. Further, as each of the predefined sequencecan be relatively long, e.g., 32 bits for example, and bettertransmission and reception reliability can be achieved compared withtraining symbols.

The foregoing is a summary and thus contains, by necessity,simplifications, generalizations, and omissions of detail; consequently,those skilled in the art will appreciate that the summary isillustrative only and is not intended to be in any way limiting. Otheraspects, inventive features, and advantages of the present invention, asdefined solely by the claims, will become apparent in the non-limitingdetailed description set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be better understood from areading of the following detailed description, taken in conjunction withthe accompanying figures, in which like reference characters designatelike elements.

FIG. 1 illustrates the format of an exemplary WUR packet including asingle signature sequence field in the preamble according to anembodiment of the present disclosure.

FIG. 2 illustrates the format of an exemplary WUR packet including morethan one sequence fields in the preamble according to an embodiment ofthe present disclosure.

FIG. 3 illustrates the format of exemplary control information in a WURpacket according to an embodiment of the present disclosure.

FIG. 4 illustrates exemplary modulation schemes for WUR packetsaccording to embodiments of the present disclosure.

FIG. 5 is a flow chart depicting an exemplary process of generating aWUR packet that uses a signature sequence to indicate a datatransmission rate in the preamble according to an embodiment of thepresent disclosure.

FIG. 6 is a flow chart depicting an exemplary process of processing areceived WUR packet that includes a signature sequence in the preamblein accordance with an embodiment of the present disclosure.

FIG. 7A illustrates the configuration of an exemplary WUR capable ofdetecting WUR packets and determining the transmission rates accordingto an embodiment of the present disclosure.

FIG. 7B illustrates the configuration of an exemplary WUR that uses asingle correlator in combination with the complementary detector todetect two complementary signature sequences according to an embodimentof the present disclosure.

FIG. 8 is a block diagram illustrating an exemplary wirelesscommunication device capable of generating wake-up packets with asequence field in the preamble according to an embodiment of the presentdisclosure.

FIG. 9 is a block diagram illustrating an exemplary wirelesscommunication device including a WUR capable of activating the mainradio responsive to a WUR packet according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications, andequivalents which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of embodiments of the present invention,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be recognizedby one of ordinary skill in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, components, and circuits have not been described indetail so as not to unnecessarily obscure aspects of the embodiments ofthe present invention. Although a method may be depicted as a sequenceof numbered steps for clarity, the numbering does not necessarilydictate the order of the steps. It should be understood that some of thesteps may be skipped, performed in parallel, or performed without therequirement of maintaining a strict order of sequence. The drawingsshowing embodiments of the invention are semi-diagrammatic and not toscale and, particularly, some of the dimensions are for the clarity ofpresentation and are shown exaggerated in the Figures. Similarly,although the views in the drawings for the ease of description generallyshow similar orientations, this depiction in the Figures is arbitraryfor the most part. Generally, the invention can be operated in anyorientation.

Efficient Preamble Design and Modulation Schemes for Wake-Up Packets inWLAN with Wake-Up Radio Receivers

Embodiments of the present disclosure provide communication protocolsfor transmitting and receiving a Wake-Up Radio (WUR) packet by using asimplified preamble structure that contains no dedicated training field.The preamble carries a signature sequence selected from a set ofpredefined sequences, each corresponding to a different datatransmission rate. The preamble and the control information of the WURpacket are transmitted in the same rate as indicated by the selectedsequence. Hence, a receiving WUR can determine the data transmissionrate and locate the associated control information directly if asequence that matches a predefined signature sequence is detected. Thesame sequence alone, or in combination with an additional sequence inthe preamble, may also be used to indicate other information such asautomatic gain control synchronization, packet type and other relatedinformation.

For example, for power preservation, a main radio in a wirelesscommunication station (STA) can be powered off or placed in a sleepstate or otherwise an inactive state. In such a state, the main radio isunable to receive or transmit packets. While the main radio is in theinactive state, the WUR of the STA remains active and can receive awake-up signal transmitted from another device, e.g., the access point(AP) STA. The WUR operates to switch the main radio back to an activestate responsive to a received wake-up signal.

FIG. 1 illustrates the format of an exemplary WUR packet 100 including asingle signature sequence field 111 in the preamble 110 according to anembodiment of the present disclosure. The WUR packet 100 encloses awake-up signal in the control information 120. The wake-up signal may bea WUR beacon signal or a signal to wake up a receiving device from asleeping mode. For example, a WUR beacon signal may be sent to the WURperiodically and provides information related to network condition,operation mode and transmission channel, and etc. In some embodiments,the WUR packet is modulated in On/Off Key (OOK) modulation and istransmitted in a narrow bandwidth (e.g., 1 MHz or 4 MHz), which canadvantageously reduce power consumption and simplify the circuitrydesign of the WUR. Upon receiving the packet, the WUR in the receivingdevice can resolve the wake-up signal in the control information. If thewake-up signal is intended to wake up the main radio in the device, theWUR generates a wake-up indication and sends it to the main radio.

The signature sequence field 111 carries a signature sequence selectedfor the packet, e.g., a 32-bit sequence. A set of signature sequencesare defined as possible values for the sequence field 111, eachcorresponding to a respective data transmission rate. At thetransmitting device, once a rate is determined for the WUR packet, acorresponding sequence is selected and assigned to the sequence field110. The preamble and the control information are transmitted in thesame data transmission rate corresponding to the selected sequence.

In some embodiments, only three possible data rates are defined for WURpacket transmission, and correspondingly three different signaturesequences, with large hamming distance, are predefined for the preamble.For instance, control information can be transmitted in a data rateselected from 125 Kbps, 250 Kbps and 500 Kbps for instances. The threesignature sequences indicate the three data rates, respectively.

Besides the data transmission rate, a signature sequence may furtherindicate a packet type. For example, two different signature sequencesare predefined, one indicative of a WUR beacon packet and the other oneindicative of a WUR packet for certain target stations.

In the illustrated example, the preamble is composed of a singlesequence field 111. A receiving device can locate the start of thecontrol information based on detection of the end of the signaturesequence in the signal stream. Moreover, because there is no trainingsymbols in the preamble which requires the lowest transmission rateregardless of the transmission rate selected for the controlinformation, it advantageously eliminates the need for changingtransmission rates during transmission of the packet as well as any needfor decoding training symbols at the receiving end. As a result, the WURpacket transmission efficiency and power efficiency can be significantlyimproved, and the pertinent circuitry design of a transmitting deviceand the WUR can be advantageously simplified. Further, as each of thepredefined sequence can be relatively long, e.g., 32 bits for instance,better transmission and reception reliability can be achieved comparedwith using training symbols as in the conventional art.

It will be appreciated that a preamble according to the presentdisclosure may include more than one sequence field. In someembodiments, the preamble also includes a AGC/Sync sequence field usedto indicate a predefined setting of automatic gain control (AGC) for aWUR to adjust the received signal strength, e.g., to reduce distortion.The AGC/Sync sequence field may further indicate a predefinedfrequency/timing synchronization setting for the WUR to obtain thecorrect start time for sampling and thereby prevent non-coherentdetection error.

FIG. 2 illustrates the format of an exemplary WUR packet 200 includingmore than one sequence field in the preamble 210 according to anembodiment of the present disclosure. In the illustrated example, thepreamble 210 has two sequence fields for indicating differentinformation. A predefined sequence in the AGC/Sync sequence field 211 isused for indicating AGC and synchronization settings, and a predefinedsequence in the signature sequence field 212 is used for indicating thedata transmission rate and possibly for indicating packet type. Thesequences in fields 211 and 222 and the control information 220 aretransmitted in the same data rate.

Thus, by using one or more sequences, a WUR preamble can effectivelyprovide indications for a set of information. Upon detection of thesequence(s) and without the need for decoding, a WUR can advantageouslyand directly ascertain reception of a WUR packet, the data transmissionrate, the preamble/control information boundary, the packet type, theAGC setting and/or a synchronization setting.

The present disclosure is not limited to any specific sequence that canbe used in the preamble. In some embodiments, each WUR signaturesequence (e.g., in field 111 or 212) is a predefined binary sequence,which can be any sequence type, such as a Barker sequence, apseudo-random sequence or a Golay sequence, etc. In some embodiments,the sequence can be OOK-modulated with Manchester coding which canprovide enhanced stability.

For example, an AGC/Sync-up sequence (e.g., in field 211) can be definedas a sequence with alternating “1” and “0” (e.g., 101010 . . . ), whereeach symbol “1” or “0” is OOK-modulated. This type of sequenceadvantageously features stability in power measurement and therefore theAGC can settle quickly at a WUR. It can also accelerate synchronizationby measuring power within each symbol. A second AGC/Sync-up sequence canbe composed of groups of multiple “1s” followed by a single “0,” such as“110110110 . . . ,” where each symbol is OOK modulated. A thirdAGC/Sync-up sequence can be composed of all “1s.”

FIG. 3 illustrates the format of exemplary control information in a WURpacket 300 in accordance with an embodiment of the present disclosure.The control information 320 may include fields that identify an AP STA(such as Basic Service Set (BSS) color) 321, and the target STA ortarget group 322 (such as the assigned ID for the station or group),wake-up control field 323 and Cyclic Redundancy Check (CRC) 324. Asimple block error control coding can be applied to the controlinformation to reduce the de-modulated errors. For example, hammingcodes, Reed-Muller codes or Reed-Solomon codes can be applied. A CRC canbe used to avoid false wake-ups caused by reception errors. The CRCfield 324 may have 4, 6, 8, 10 or 12 bits for example.

To reduce power consumption and simplify WUR design, OOK modulation canbe used in WUR packets. FIG. 4 illustrates 3 exemplary modulationschemes of WUR packets according to embodiments of the presentdisclosure. Diagram 410 shows an embodiment in which the preamble andthe control information are both modulated by ON/OFF Keying, each ON/OFFsymbol can be 3 μs or 4 μs in length and each symbol may contain 1 bitinformation for example. Diagram 411 shows another embodiment in whichthe preamble and the control information are both modulated by ON/OFFKeying with Manchester coding. Diagram 413 shows still anotherembodiment in which the preamble uses ON/OFF Keying while the controlinformation uses ON/OFF Keying with Manchester coding. Using the hybridmodulation scheme as in diagram 413 can achieve high efficiency inpreamble communication as well as high reliability in controlinformation communication

FIG. 5 is a flow chart depicting an exemplary process 500 of generatinga WUR packet that includes a signature sequence to indicate datatransmission rate in the preamble in accordance with an embodiment ofthe present disclosure. Process 500 may be performed by a wirelesstransmitting device, such as an AP STA or a non-AP STA. At 501, a datatransmission rate for the WUR packet is accessed. The data transmissionrate is selected from a set of permissible rates. The present disclosureis not limited to any specific mechanism for selecting or determining adata transmission rate for a particular WUR packet. At 502, a signaturesequence is selected from a set of predefined signature sequences basedon the selected data transmission rate and inserted in the preamble. Thenumber of predefined signature sequences may correspond to the number ofpermissible data transmission rates that are defined in an exemplary WURprotocol. The signature sequence itself indicates the rate. At 503, thecontrol information or the payload is generated and includes a wake-upsignal directed to a WUR. The control information may include severalfields as shown in FIG. 3. At 504, the WUR packet is transmitted througha wireless network channel using the same data transmission rate forboth the preamble and the control information.

FIG. 6 is a flow chart depicting an exemplary process 600 of processinga received WUR packet that uses a signature sequence in the preamble inaccordance with an embodiment of the present disclosure. Process 600 maybe performed by a WUR in a wireless receiving STA. At 601, a signalstream is received at the WUR. At 602 and 603, the WUR determineswhether one of the set of predefined signature sequences is detected inthe signal stream. In this example, there are only two signaturesequences defined for a single sequence field of WUR preambles, eachcorresponding to, and would be transmitted in, a respective datatransmission rate. Thus, if either signature sequence is detected, theWUR can directly determine the corresponding data rate 604. At 605, theboundary between the preamble and the control information can bedetermined once the end of the signature sequence is detected as itslength is known. At 606, the control information is resolved accordingto the determined data transmission rate. At 607, if it is determinedthat the instant device is the intended device and the wake-up signal inthe control information indicates to activate the main radio, the WURgenerates a wake-up indication and sends it to the main radio.

FIG. 7A illustrates the configuration of an exemplary WUR 700 capable ofdetecting WUR packets and determining the transmission rates inaccordance with an embodiment of the present disclosure. The WURincludes an automatic gain controller (AGC) 701, an RF local oscillator702, a mixer 703, a low pass filter 704, an analog-to-digital converter(ADC) 705, and two correlators 711 and 712.

The WUR 700 can receive signals of a wake-up packet through a receiveantenna (not shown). The AGC 701 includes an attenuator and controls themagnitude or gain of the received signal. A baseband filter (not shown)filters the RF signal and the RF local oscillator 702 oscillates an RFfrequency while shifting to a center frequency of the wake-up signaldirected to the WUR 700 and outputs an RF local oscillation frequency tothe mixer 703. The mixer 703 converts the RF signal from the basebandfilter into a baseband signal by using the RF local oscillationfrequency output from the RF local oscillator 702. The LPF 704 filtersthe baseband signal supplied from the mixer 703 while adjusting to thebandwidth of the wake-up signal. The ADC 705 converts the analogbaseband signal output from the LPF 704 into a digital baseband signal,and the correlators 711 and 712 operates to detect a signature sequencein the converted signal.

In this example, there are two data rates (Rate 1 and Rate 2) definedfor WUR packet transmission and therefore two signature sequences aredefined. Each signature sequence is to be transmitted at itscorresponding data rate. Each of the correlators 711 and 712, incombination with the rate detection module 713, tries to compare theconverted signal with a respective signature sequence according to thecorresponding data rate. Upon either of the correlators detecting amatch between the converted signal and a signature sequence, the WUR candecide that the received signal carries a WUR packet and can alsoidentify a data transmission rate of the WUR packet. The WUR 700 alsoincludes an OOK signal detector (not explicitly shown) for demodulatingthe digital baseband signal output from the ADC 705. In someembodiments, the WUR may also include additional correlators incombination with detection modules configured to determine packet type,AGC and synchronization settings as indicated by another sequence fieldin the preamble.

In the embodiment shown in FIG. 7A, the number of correlators in the WUR700 may be the same as the set of predefined signature sequences, andeach correlator is configured to detect a respective sequence in thecorresponding data transmission rate. In some other embodiments, the setof predefined sequences include a pair of complementary sequences, e.g.,corresponding to a low data rate and a high data rate, respectively. Forexample, for the low data rate, the signature sequence is predefined asS; and for the high data rate, the signature sequence is predefined asthe complementary sequence of S or a partial complementary sequence ofS. Thus, a single correlator suffices to determine whether the signalcontains either complementary sequence. FIG. 7B illustrates theconfiguration of an exemplary WUR 750 that uses a single correlator 751in combination with the complementary detector 752 to detect twocomplementary signature sequences in accordance with an embodiment. Thiscan advantageously simplify the correlator/sequence detector design.

It will be appreciated that the preamble structures disclosed herein canbe used in single-user (SU) or multi-user (MU) WUR packets. Thecommunication devices according to embodiments of the present disclosuremay have main radios configured to use one or more wirelesscommunication technologies, such as Bluetooth®, WI-FI and/or cellulartechnologies, e.g., LTE, 4G, 5G, etc.

FIG. 8 is a block diagram illustrating an exemplary wirelesscommunication device 800 capable of generating wake-up packets with asequence field in the preamble in accordance with an embodiment of thepresent disclosure. The communication device 800 may be an AP or non-APdevice having a transceiver configured for data communication, e.g., ageneral purpose computer, a smart phone, a portable electronic device, atablet wearable device, a sensor used on Internet of Things (IoT), andetc.

The device 800 includes a main processor 830, a memory 820 and atransceiver 840 coupled to an array of antenna 801-804. The memory 820includes a wake-up manger 821 that stores processor-executableinstructions for generating preamble sequences and wake-up signals aswell as configurations of other parts of WUR packets, as described ingreater detail with reference to FIGS. 1-5. The wake-up manager 821 alsostores other information related to WUR packet generation andmanagement, such as the STA IDs, STA group IDs, sleep protocols of themain radios and WURs of the STAs, negotiation protocols, frequencysub-channels allocated to the respective WURs, MU wake-up packetformats, and so on. In some other embodiments, the wake-up manager 821is stored in a memory within the transceiver 840.

The transceiver 840 includes an OOK baseband module 841, a pulse shapingmodule 842 and digital mixing module 843 which operate to generateOOK-modulated wake-up signals as well as preamble sequences as describedin greater detail with reference to FIG. 1-5. The transceiver 840further includes various modules of the transmit path which isconfigured to generate each section of a WUR packet or data packet orany other type of communication transmission units. For instance, it hasa transmit First-In-First-Out (TX FIFO) 844, an encoder 846, a scrambler845, an interleaver 848 a constellation mapper 847, an inversed discreteFourier transformer (IDFT) 849, and a GI and windowing insertion module850.

FIG. 9 is a block diagram illustrating an exemplary wirelesscommunication device 900 including a WUR 950 capable of activating themain radio 941 responsive to an WUR packet in accordance with anembodiment of the present disclosure. The device 900 may be a non-AP STAoperable to perform data communication with other devices through awireless LAN. The device 900 may be a general purpose computer, a smartphone, a portable electronic device, a tablet wearable device, a sensorused on Internet of Things (IoT), and etc.

The device 900 includes a main processor 930, a memory 920 and atransceiver 940 coupled to an antenna 901. The transceiver 940 includesa main radio 941 operable to enter into an inactive state for powerconservation. The low power wake-up radio (WUR) 950 can process an WURpacket and accordingly generate an indication to activate the main radio941. Particularly, the WUR 950 includes an AGC 951, a mixer 952, an LPF953, correlators 9532 and an OOK signal detector as described in greaterdetail with reference to FIGS. 7A-7B.

Various modules in the main radio 941 are configured to process receiveddata packets or any other type of communication transmission units. Asillustrated, the main radio includes a receiving First-In-First-Out (RXFIFO) 942, a synchronizer 943, a channel estimator and equalizer 944, adecoder 946, a demapper 945, a deinterleaver 949, a fast Fouriertransformer (FFT) 948, and a descrambler 947.

It will be appreciated that the transceiver 840 in FIG. 8 and thetransceiver 940 in FIG. 9 may include a wide range of other suitablecomponents that are well known in the art. The various components can beimplemented in any suitable manner that is well known in the art and canbe implemented using hardware, firmware and software logic or anycombination thereof. Further, in some embodiments, the transceiver 840in FIG. 8 may as well include the components in a receiving path asdescribed in greater detail with reference to the main radio 941 in FIG.9, and vice versa.

Although certain preferred embodiments and methods have been disclosedherein, it will be apparent from the foregoing disclosure to thoseskilled in the art that variations and modifications of such embodimentsand methods may be made without departing from the spirit and scope ofthe invention. It is intended that the invention shall be limited onlyto the extent required by the appended claims and the rules andprinciples of applicable law.

What is claimed is:
 1. A method of wireless communication, said methodcomprising, generating a wake-up radio (WUR) packet comprising a wake-upradio signal for a wake-up radio of a wireless communication device,wherein said generating comprises: accessing a data transmission ratefor transmitting said wake-up radio signal; selecting a predefinedsequence from a plurality of predefined sequences based on said datatransmission rate, wherein each of said plurality of predefinedsequences is operable to indicate a different data transmission rate forWUR packet transmission; generating a preamble for said WUR packet,wherein said preamble comprises said predefined sequence; and generatingcontrol information for said WUR packet; and transmitting both saidpreamble and said control information in said WUR packet using said datatransmission rate.
 2. The method of claim 1, wherein said generatingsaid WUR packet further comprises modulating said preamble and saidcontrol information using On/OFF Key (OOK) modulation.
 3. The method ofclaim 1, wherein an end of said predefined sequence corresponds to aboundary between said preamble and said control information, whereinsaid control information comprises: an identification of a Basic ServiceSet (BSS); an identification of said wireless communication device; andsaid wake-up signal.
 4. The method of claim 1, wherein said preamblecomprises a single field that comprises said predefined sequence.
 5. Themethod of claim 1, wherein said WUR packet is free of training symbol.6. The method of claim 1, wherein each of said plurality of sequences isfurther operable to indicate a respective WUR packet type.
 7. The methodof claim 1, wherein said plurality of sequences comprise complementarysequences.
 8. The method of claim 1, wherein said preamble furthercomprises another predefined sequence selected from another plurality ofpredefined sequences, wherein said another predefined sequence providesone or more of: automatic gain control and synchronization informationassociated with said WUR packet.
 9. A wireless communication devicecomprising: a memory; a processor; and a first radio configured totransmit and receive data packets in an operational mode; and a secondradio coupled to said first radio and configured to: receive an incomingsignal; detect a predefined sequence from said incoming signal; identifya preamble of a wake-up radio (WUR) packet from said incoming signal,wherein said preamble comprises said predefined sequence; identifycontrol information of said WUR packet from said incoming signal basedon detection of said predefined sequence; resolve said controlinformation based on a data transmission rate indicated by saidpredefined sequence; and generate a wake-up indication based on saidcontrol information, wherein said wake-up indication is operable tocause said first radio to exit from a low power mode and to enter saidoperational mode.
 10. The wireless communication device, wherein saidsecond radio comprises an On/OFF Key (OOK) detector configured todemodulate said incoming signal.
 11. The wireless communication deviceof claim 9, wherein said second radio is configured to identify saidcontrol information by identifying an end of said predefined sequence asa boundary between said preamble and said control information.
 12. Thewireless communication device of claim 9, wherein said second radiocomprises a plurality of correlators configured to respectively identifya plurality of predefined sequences from incoming signals, wherein eachof said plurality of correlators corresponds to a different datatransmission rate and is configured to determine a correspondingpredefined sequence according to a data transmission rate associatedtherewith.
 13. The wireless communication device of claim 9, whereinsaid second radio comprises a correlator configured to identify twocomplimentary predefined sequences from incoming signals.
 14. Thewireless communication device of claim 9, wherein said second radio isfurther configured to identify another predefined sequence comprised insaid preamble, wherein said another predefined sequence indicates one ormore of: automatic gain control and synchronization informationassociated with said WUR packet.
 15. The wireless communication deviceof claim 9, wherein said WUR packet is free of data training symbol. 16.A wireless communication device comprising: a memory; a processorcoupled to the memory; and a transceiver coupled to said memory, whereinsaid transceiver is configured to: generate a wake-up radio (WUR) packetcomprising a wake-up radio signal for receipt by a WUR of a wirelesscommunication device, wherein said wake-up radio packet is generated by:selecting a predefined sequence from a plurality of predefined sequencesbased on a data transmission rate for transmitting said wake-up radiosignal, wherein each of said plurality of predefined sequences isoperable to indicate a different data transmission rate for WUR packettransmission; generating a preamble for said WUR packet, wherein saidpreamble comprises said predefined sequence; and generating controlinformation for said WUR packet; and transmit both said preamble andsaid control information in said WUR packet at said data transmissionrate.
 17. The wireless communication device of claim 16, wherein saidtransceiver is also configured to modulate said preamble and saidcontrol information using an On/OFF Key (OOK) modulation process. 18.The wireless communication device of claim 16, wherein an end of saidpredefined sequence corresponds to a boundary between said preamble andsaid control information, and wherein said control informationcomprises: an identification of a Basic Service Set (BSS); anidentification of said wireless communication device; and said wake-upsignal.
 19. The wireless communication device of claim 16, wherein saidpreamble comprises a single field that contains said predefinedsequence, and wherein said WUR packet comprises no training symbol. 20.The wireless communication device of claim 16, wherein said plurality ofsequences comprise complementary sequences.
 21. The wirelesscommunication device of claim 16, wherein said preamble furthercomprises another predefined sequence selected from another plurality ofpredefined sequences, wherein said another predefined sequence providesone or more of: automatic gain control; WUR packet type; andsynchronization information associated with said WUR packet.